Automatic disconnecting switch



0d. 19,1937. 'J. J. SHOEMAK'E'R ET AL 2,096,705

AUTOMATIC DISGONNECTING SWITCH Filed June 3, 1931 5 Sheets-Sheet l -19,1931. J.J.SHOEMAK ERETAL 2,096 706 AUTOMATIC DISCONNECTING SWITCH FiledJune 3, 1931- 3 Sheets-Sheet 3 I gram/Eris Jasep cf 67.10%4/561?Patented Oct. 19, 1937 v UNITED STATES PATENT OFFICE Schwarz,

Royal Oak, Mich.,

assignors, by

mcsne assignments, to Westinghouse Electric & Manufacturing Company, acorporation of Pennsylvania 4 Application June 3, 1931,'Serial No.541,776

16 Claims.

This invention relates in general to electricalswitches and is moreparticularly concerned with improvements in electrically operatedswitches of the disconnecting type, which are designed for working undervoltage and current conditions such as are ordinarily met with insecondary distribution systems, wherein the switch is opened only whenthere is little or no load on the circuit as distinguished from switcheshaving relatively high interrupting capacity and which are adapted foropening under load conditions.

It is a primary object of this invention to provide in a disconnectingswitch, operating means whereby the switch may be closed and opened froma distance by energizing and deenergizing the circuit in which thecontacts of the switch are disposed.

It is a further object of this invention to provide in a disconnectingswitch, improved means for interlocking the main contacts of the switchin closed position as soon as either current or voltage is establishedon the circuit in which the switch contacts are disposed, and which willfunction to open the contacts upon the circuit being entirelydeenergized or when-both the current and voltage have been reduced to apredetermined value.

It is a further object of this invention to provide a switch havingelectrically responsive closing means which is mechanically interlockedin closed position, and in which actuation of the in- 3 terlockingmechanism is efiective to deenergize the switch closing means.

It is likewise an object of this invention to provide in a disconnectingdevice contacts of the high pressure type which are so designed that anyoxidation, dirt and the like thereon will be readily crushed and willnot interfere with the establishing of.a good electrical circuit throughthe switch contacts.

It is a further object of this invention to provide in a disconnectingswitch, improved auxiliary means for interrupting the closing coilcircuit of the switch as soon as the main switch contacts are in closedposition.

Another object of this invention is to provide an automaticdisconnecting switch which is adapted for mounting in the tank of atransformer so as to form a self-contained distribution device adaptedfor use in network distribution systems, wherein the primary feedcurrent of the transformer will be effective to energize the operatingmechanism of the switch, the switch contacts being disposed in thesecondary circuit of the transformer, whereby the sec- 55 ondary leadsof the transformer may be automatically opened when the primary supplyis opened with the result that back feed through the transformer isprevented.

Other objects of this invention will more fully appear from thefollowing detail description 5 taken in connection with the accompanyingdrawings which illustrate asingle embodiment thereof, and in whichFigure 1 is a side elevation of a disconnecting switch embodying thefeatures of our invention; 10

Figure 2 is a plan view of the switch showing the main contacts and therelationship of the current and potential elements of the interlockingmechanism;

Figure 3 is an end elevation of the switch;

Figure 4 is a vertical sectional view through the switch showing themain contacts in closed position, and the relative positions of thevarious elements comprising the interlocking mechanism of the switch,taken substantially on line IVIV of Figure 2;

Figure 5 is a view similar to Figure 4 except that themain contacts arein open position and the various elements of the interlocking mechanismare in unlatched position; 25

Figure 6 is a cross sectional View through the tank of a transformerhaving the switch of our invention applied thereto; and

Figure 7 is a diagrammatic view showing the electrical connectionsbetween the elements com- 30 prising the switch of our invention.

As shown on the drawings:

In the illustrated embodiment of our invention. we have shown thedisconnecting switch as being assembled upon a horizontally disposedpanel. III of insulating material, which is supported on a pair ofspaced members ll-l l, these members being secured to the panel in anyappropriate manner, as by bolts I2.

The-disconnnecting switch proper consists of stationary contact membersl3 and I4 which are arranged for engagement by a cooperating movablecontact member IS. The faces of the stationary contact members, withwhich the movable contacts engage, are arranged at an angle ofapproximately the engaging surface of 'the movable contact member beingarcuate in form so that they will be self-aligning and at all times makeproper contact with the faces of the stationary contactmembers.

The stationary contact [3 is in the form of a bar of material ofsuitable electrical conductivity and is disposed in a channel shapedmember a of insulating material. The upper surface of the bar formingstationary contact I! is exposed which is secured against the bar bymeans of nuts l6 which threadedly engage the ends of bolts l1 whichextend through the bar, thereby enabling the nuts I6 to be tightenedagainst associated washers I8 which engage the terminal connection.

The nuts I 6 also cooperate with the bolts- IT to rigidly secure thestationary contacts l3 against the upper surface of the panel Ill.

The stationary contact [4 is likewise secured to the upper surface ofthe panel l0 and is in the form of a bar of material of good electricalconductivity, the outer end of the bar being deflected to form a rightangle portion N to which a terminal connector may be secured as bysuitable bolts 2! which threadedly engage the bar. This bar is disposedin a channel shaped insulating member'22 which is similar to the memberMa associated with the stationary contact l3. Extending over the uppersurface of the bar forming the stationary contact I4 is another channelshaped member of insulating material as shown at 23 which cooperateswith member 22 to insulate the bar for a purpose that will besubsequently described.

The movable contact I5 is connected to the upper end of a member 24which extends downwardly through an aperture 25 in the panel I 0 asshown in dotted lines in Figure 4. This aperture is constructed so asto'have sufiicient clearance to enable slight pivotal movement of themember 24, this member being pivoted at its lower end between the endsof a substantially horizontally ,disposed member 26. .This aperture alsoserves as a guide for the member 24 when it is moved longitudinally tobring the movable contact l5 into and out of engagement with thestationary contacts l3 and M. In order to relieve the pivotal connectionbetween members 24 and 26 from excessive strain and wear when closingthe switch contacts, member 26 is formed with a projecting portion 26awhich abuts the lower end of member 24 as shown in Figure 1.

Power means for closing the main contacts of the switch consist of amagnetizable core 21 operatively associated with an armature 28 which issupported for movement when influenced by the magnetization of the core21. The core 21 is in the form of a U and is made up of a plurality oflaminations which are clamped between spaced 34 which surrounds one legof the core and projects through windows or openings 35 in-the framemembers 29 and 3D. The armature 28 is likewise composed of a pluralityof laminations 36 which are secured between a plurality of spacedclamping members 37. These clamping plates together with the outermostlaminations are extended and apertured for receiving therethrough apivot pin 38 having its ends projecting through extended portions of thespaced frame members 29 and 30 so as to form a pivotal mounting for thearmature.

Pivotal movement of the armature 28 is transmitted to the/movablecontacts l5 of the disconnecting switch through a series ofinterconnected links. Each member 26 is associated with one of themovable contacts of the disconnecting switch and pivotally connected atone end to a for engagement by a terminal connection I5a' yoke member 39which is pivotally connected to and cooperates with a pair of linkmembers 40 and 4| disposed on either side of the armature to form asubstantially vertical toggle.

The link members 40and 4i are pivoted at their lower ends on pivot pin38. This toggle is actuated by means of a substantially horizontaltoggle consisting of links 42 and .43, the outer end of the link 42being pivotally connected to the main toggle at the pivotal connectionbetween its members. The member 43 is in the form of a crank disposed ateither end of a cylindrical sleeve 44 which is rotatably mounted on apivot pin 45 having its ends supported in a bracket 46 secured to anddepending from the panel In. Angularly displaced from the pivotalconnection of the member 43 to the link 42, the member 43 is pivotallyconnected to one end of a link member 41, its other end being pivoted ona rod 48 which extends transversely through the upper portion ofclamping members 31 and the outermost laminations of the armaturecontained therebetween. I

The other end of member 26 is floatingly fulcrumed by being pivotallyconnected to the upper end of a supporting member 49 which extendsdownwardly through an aperture in a bracket 50 formed on each of theframe members 29 and 39, the lower end of the member 49 being threadedfor receiving a nut 5|. Disposed around the member 49 above the bracket59 is a coil spring 52 which is compressed between the members 26 and49. The foregoing arrangement provides a floating fulcrum for member 26and also enables adjustment of the pressure between the movable contactl5 and the stationary contacts l3 and M by tightening or loosening thenut 54 against the spring 52. It will also be observed by reference toFigure 1 that, when the contacts of the disconnecting switch are closed,the nut 5i is spaced from the bracket 50, and that, when the movablecontact is disengaged from the stationary contact, the spring 52 willforce the supporting member 49 upwardly until the nut 5| bears againstthe under surface of bracket 50. This provides sufficient leeway tocompensate for any wear which may take place between the contacts of theswitch.

The interlocking mechanism for the switch, which is arranged to lock thetoggles in extended position when the contacts of the switch are closed,comprises a cam plate 56 which is secured to the sleeve 44 and isangularly disposed from the crank member 43, Figures 4 and 5. The camplate 56 is formed with a concentric slot 51 which terminates at one endin an upwardly extending recessed portion 58 which forms a dwell for aroller 59 which is disposed for movement through the slot. The roller 59is carried by an armature 60 secured to a shaft 6| which is rotatablytrunnioned in the bracket 46. The armature 59 is operatively associatedwith a core 62 which is magnetized by a potential coil 63, the corebeing supported on the panel l0 and projecting into a suitable aperture64. By making the recessed portion 58 of the slot 51 substantiallv halfthe diameter of the roller 59, a definite clearance is establishedbetween the pole faces of the core 82 and the armature 60, when thearmature is in closed position.

With the disconnecting switch closed, the recessed portion 58 willbedisposed above the roller 59, so that if the coil 83 is energized thearmature 60 will be attracted and move the roller into the recessedportion, thereby latching the toggle mechanism in closed position. Sincethe disconnecting switch is latched in closed position, it is not nownecessary to maintain the closing coil 34 energized. In order to openthe circuit to this coil an auxiliary switch is provided which isactuated by the movement of armature 68. For this purpose the armature60 is extended to form an arm 65 which bears against the lower end of amember 68 which is vertically reciprocable relative to the panel In.Secured to the upper end of the member 86 is a conical shaped memberwhich forms the movable contact of the auxiliary switch. Disposed belowthe movable contact 61 is a stationary contact 68 which is formed with aconical surface for cooperatively engaging the conical surface of themovable contact, the stationary contact surrounding the member 88 andbeing secured to the panel [8 by a threaded sleeve portion 59. Themovable contact is normally held in engagement with the stationarycontact by means of a spring 10 which is disposed within a pocket Ii inthe underside of the panel Hi and surrounds the member 66. This springis compressed between the sleeve portion 59 of the stationary contactand a washer 12 which is secured against downward movement on the member86 by means of a pin I3. Surrounding the stationary contact is a coil 14which serves as a blow out coil for any arc which may be formed betweenthe contacts of the auxiliary switch when they are opened.

In the arrangement just described, it will be observed that the fluxlines in the magnetic field set up by the blowout coil will, since thiscoil has an air core, emanate outwardly in a direction substantiallyparallel to the conical surfaces of the contacts 61 and 68. Any arewhich is formed between the contacts will therefore be substantially atright angles to the field flux through which it passes and will becaused to move or be rotated circumferentially around the axes of thecontacts, the arcs thereby being carried into cooler portions of thecontact surfaces and extinguished without damage to the contacts.

In addition to the potential element of the interlocking mechanism,there is also provided a current element which is associated with eachof the stationary contacts I 4 and comprises a plurality of circularlyformed laminations 15 which surround the member I and are insulatedtherefrom by the channel shaped members 22 and 23 of insulatingmaterial. These laminations are secured between spaced members 16 in anywellknown manner. Outwardly extending from the members 18 and overlyingthe bar composing the stationary contact I is a metallic member 18awhich is secured to the panel l0 as by bolts 11, and forms an inductiveshield between the current and potential elements of the interlockingmechanism. The laminations 15 extend into suitable apertures in thepanel in and are arranged for operatively affecting an armature 18,Figure 3, which is secured to and movable with shaft 8|. Since thearmatures of both the cur rent and potential elements of theinterlocking mechanism are fixedly secured to the common below the oillevel in the transformer.

shaft 8i, it will be apparent that the disconnecting switch may belocked in closed position by virtue of the energization of either thepotential or current elements. In, the arrangement of the currentinterlock or latch just described, it will be observed that the magneticpull on armature 18, with a given constant current value, may beincreased or decreased by increasing or decreasing the number oflaminations used to make up cores l5 and armatures 18.

In order to provide means for opening the switch contacts when thecurrent and potential elements of the interlocking mechanism aredeenergized, the cam plate 56 is extended to form a lug I9, Figures 4and 5, which is engaged by one end of a tension spring having its otherend secured to an adjustable screw 8| which threadedly engages thebracket 48, this screw being provided with a nut 82 by means of whichthe screw may be locked in adjusted position. By varying the amount ofiron in core I5 and armature 18, or increasing or decreasing the tensionon spring 80, the switch can be arranged to remain closed with anydesired combination of voltage and current within a wide range. Thus,the switch will remain closed under high current and low voltageconditions, but will open with low voltage and low current. In thismanner the switch will remain closed when energy is supplied to a shortcircuit, but will open very quickly when the circuit is de-energized.

of our invention is shown as being applied to a transformer to form adistribution unit which is exceedingly advantageous for use indistribution systems such as disclosed in United States Patent No.1,979,353.

In this unit the disconnecting switch is supported upon the transformercore structure by means of a plurality of spacer members 83, in such amanner that the switch is preferably disposed By thus mounting theswitch within the transformer tank, the oil therein serves to insulatethe switch from the elements, thereby being conducive to longer life andfreedom from trouble due to possible corrosive formations on the variousparts. In this form of our invention, the secondary leads of thetransformer, that is, the ends of the secondary winding are connected tothe stationary contacts I and the stationary contacts i 3 are connectedby means of terminal connections l5a to the secondary terminals of thetransformer. The central point of the secondary winding is also broughtout to a transformer terminal through conductor 84, thereby enabling thedistribution unit to be used for either two wire or three wiredistribution.

1 The operation of our invention will be as folows:

Referringto Figure 7, the primary winding of the transformer isconnected through terminal leads 88 and 81 to an electrical circuit. Thesecondary winding 88 of the transformer is connected through conductors88 and 80 to the stationary contacts ll of the disconnecting switch andthe stationary contacts l3 of the disconnecting switch extend throughterminal connections I 5a'--l5a.

Energization of the primary winding 85 will put secondary voltage on thestationary contacts 89, conductor 8| through contacts 88 and 61 of theauxiliary switch, conductor 82, blow out coil M, conductor 93 to oneterminal of the coil 36, from the other terminal of the coil 34! throughconductor as and the conductor to the other terminal of the secondarywinding of the transformer. Coil 38 being energized will actuate thecontacts lb of the disconnecting switch into engagement with theirassociated stationary contacts i3 and M, thereby applying voltage to theterminal connections l5a.

Simultaneously with the energizing of coil 343, the potential element ofthe interlocking mechanism is actuated by virtue of coil 63 beingenergized through the following circuit: from one terminal of thesecondary win-ding of the transformer, through conductor 89, conductor9i, conductor to one terminal of coil 63, from the other terminal ofcoil 63 through conductor 96 and conductor 95 to the other terminal ofthe transformer secondary Winding. When coil 63 is energized, themagnetized core 62 therein attracts armature 50, which action moves eacharmature 78 towards its associated magnet and also opens contacts 67 and68 of the auxiliary switch. Opening of these contacts causes an arc tobe formed therebetween due ,to the inductive efiect of the coil 3Q, butsince the current flowing through this are also flows through the blowout coil M, which is in series with the contacts 6'3 and 68, the are isextinguished.

As soon as load is applied to the transformer, current will flow fromthe transformer through the contacts ,of the disconnecting switch andmagnetize the laminatio-ns l5 which assist the potential element of theinterlocking mechanism in maintaining the disconnecting switch contactslocked in closed position. Referring to Figure 5, which shows theinterlocking mechanism in nonlocked position, it will be observed thatthe roller 59 on the armature Ell is dsposed in the end of slot 57 whichis opposite from the'end of the slot having the recessed portion 58therein. When the armature 28 is attracted by the magnet N in closingthe disconnecting switch, the cam plate 56 is rotated clockwise to theposition shown in Figure 4, in which position the roller is disposedbeneath the recessed portion 58 of the slot. Now, when the armature tillis attracted by the magnet 72 as describedabove, the roller w'll bemoved into the recessed portion and mechancally latch the cam plate 56against rotational movement.

With either the voltage or current elements of the interlockingmechanism excited, the switch will be maintained interlocked in closedposition. However, as soon as both current and voltage have beendecreased to a predetermined value. this value being the drop-out valueof the respective armatures, or, if, the current and potential elementsare deenerg zed by d sconnecting the transformer from the electricalsupply circu t, the armatures E9 and 78 will be released. Since thearmatures are connected to a common shaft. the roller 59 is moved out ofthe recessed portion 58 of the slot, thus releasing the cam plate 56which is rotated counter-clockwise by means of the tension spring 80.Rotation of the cam plate 56 will rotate sleeve 64 and the crank members63 secured thereto, thereby causing the toggles to move the contacts l5out of engagement with the stationary contacts is and Hi; the variouselements of the disconnecting switch being now disposed as shown inFigure 5.

Now, it is of course to be understood that although wehave described indetail the preferred embodiment of our invention, the invention is notto be thus limited but only insofar as defined by the scope and spiritof the appended claims.

We claim as our invention:

1. In a disconnecting switch, contacts actuatable to open and close anelectrical circuit, means for actuating said contacts, and means forlatching said contacts in closed position, said means being actuatableto locking position by current and potential elements connected to saidcircuit and arranged to be energized when the circuit is energized.

2. In a disconnecting switch, contacts arranged for opening and closingan electrical circuit, means for actuating said contacts, and means forlatching said contacts in closed position comprising current andpotential elements energizable from said circuit, and a mechanicallinkage having a common connection with said elements and actuated tolatching position upon the energization of said elements.

3. In a disconnecting switch having relatively movable main contacts foropening and closing an electrical circuit and means energizable to'actuate said contacts to closed position; means for de-energizing saidfirst means when the main contacts are closed comprising relativelymovable contact members having conical surfaces of engagement, and a.blow out coil, so located with respect to said conical surfaces that itsflux is substantially parallel to said surfaces.

4. In a disconnecting switch having relatively movable members foropening and closing an electrical circuit and means energizable toactuate said members to closed position; means for de-energizing saidfirst means when the members are closed comprising normally closedcontacts having conical surfaces of engagement, and a blow out coil solocated with respect to said conical surfaces as to produce rotation ofthe are formed between said surfaces.

5. A switch comprising normally closed and relatively movable contactshaving conical surfaces of engagement, and a blow out coil parallel tothe conical surfaces, said coil and contacts being connected in series.

6. A disconnecting switch comprising spaced stationary contacts, amember resiliently fulcrumed at one.end, a toggle mechanism connected atthe other end of said member, electroresponsive means for actuating saidtoggle mechanism', and a contact member connected to and reciprocable bysaid first member into engagement with said stationary contacts whensaid electro-responsive means are energized, said resilient fulcrumbeing so mounted with respect to the contacts and having partscooperative in such a manner as to oppose the separation of the contactswhen they are in engagement.

'7. A disconnecting switch comprising stationary contacts, a link memberresiliently fulcrumed at one end, a toggle mechanism connected at theother end of said link member, electro-responsive 'means for actuatingsaid toggle mechanism, a

circuit, said elements having separate magneticcircuits and relativelydisposed with the potential element between the current elements.

control means for said contacts including coilmeans responsive to thecircuit potential and coil means responsive to the circuit current, saidcontrol means maintaining said contacts in latched position uponenergization of either of said coil means, and connecting means betweensaid coil means whereby said circuit may be opened when said' currentand said voltage both reach-a predetermined low value.

' I 11. In a switch control means for an electrical circuit, meansincluding a toggleto maintain the switch closed, a circuit current coil,a circuit potential coil, and toggle operating means associated withsaid coils, said latter means being operative to open said circuit whenthe current and voltage respectively of said coils reaches apredetermined low value.

12. In a switch control means for an electrical circuit, means includinga toggle to maintain the switch closed, a circuit current coil, 'acircuit potential coil; and toggle operating means associated with saidcoilsand operative to open said switch,

said operating means including a plurality of armatures having a commonyieldable pivot.

13. In a switch control means for an electrical circuit, means includinga toggle to maintain the switch closed, a circuit current coil, acircuit potential coil, and toggle operating means associated with saidcoils, and operating to open said circuit when the current and voltagerespectively of said coils reaches a predetermined low value, saidoperating means including a plurality of armatures having a commonyieldable pivot.

14. In a disconnecting switch, main contact members, means for actuatingsaid contacts to open position, latch mechanism for maintaining saidcontact members in closed position against the force of the openingmeans, and voltage responsive means effective upon energization above apredetermined degree to close and latch the main contacts, and meansefiective upon de-energization to a predetermined low value of voltageand current to trip said latch mechanism.

15. In a switch apparatus, main contact members, means for biasing saidcontact members to open position, latch mechanism for restraining saidcontact members in closed position against the force of said biasingmeans, electro-magnetic closing means for said contact members andelectro-responsive' means effective when energized below a predetermineddegree to connect said closing means for energization and effective whenenergized above a predetermined degree to disconnect said closing meansand oppose the opening of said latch mechanism. 2

16. An alternating current tripping mechanism comprising a movabletripping member operable to a tripping position, an electro-magneticactuating element energized solely in accordance with a potentialcondition for moving said member to non-tripping position, and a secondelectro-magne'tic elementenergized in accordance with a currentcondition for cooperating with the first element for preventing movementof said member to tripping position except upon predetermined currentand voltage conditions.

JOSEPH J. SHOEMAKER. RICHARD E. SCHWARZ.

